<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
      <style type="text/css">
        div{
            width:100px;
            height:100px:
            font:30px;
        }

        #div2{
            background:#ffaa00;
        }
        .test{
            color:#abcdef;
        }
        .div3{
            background:#00ff00;
        }
    </style>

</head>
<body>
    <div id="div1" class="div1 test" style="width:200px;height:200px;background:black">测试数据1</div>
    <div id="div2" class="div2 ">测试数据2</div>
    <div id="div3" class="div3 ">测试数据3</div>
</body>

</html>